From the Chassidic Masters

Pinchas' deed evokes many associations -- courage, decisiveness and religious passion are several that come to mind -- but peace hardly seems one of them. Pinchas, after all, killed two people. So why does the Torah describe him as a man of peace? To understand Pinchas' place in the Jewish consciousness, we first need to understand the Torah's conception of the "zealot" (kana'i). Is violence ever a positive trait? Is the zealot the ultimate altruist, or just an angry young (or old) man who has found a holy outlet for his aggression?